ADSM-L

Re: Does Reclamation work for Tape Capacity?

2001-01-24 15:40:20
Subject: Re: Does Reclamation work for Tape Capacity?
From: S W Branch <swbranc AT PPCO DOT COM>
Date: Wed, 24 Jan 2001 14:41:46 -0600
Copied directly from the TSM 4.1 Administrator's Guide at Tivoli's Web site
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For offsite volumes, reclamation can occur when the percentage of unused
For offsite volumes, reclamation can occur when the percentage of unused
space on the volume is greater than the reclaim parameter value. The unused
space includes both space that has never been used on the volume and space
that has become empty because of file deletion.


What are your Estimated Capacity and Percent Utilized values? I guess that
TSM subtracts the amount of data written on the tape from the estimated
capacity to come up with the amount of space that has never been used - I
can't think of any other value that TSM could use. If this is true and if
your estimated capacities are less than the amount of data written on the
tapes TSM won't be able to calculate an unused portion. This might be the
cause of what you are seeing when you lower the reclamation percent and yet
don't see reclamation run as expected. It appears that TSM sets the
estimated capacity for a tape to the amount written once you have exceeded
the estimated capacity specified for the device class (or the default if
not specified).